To modify corncob by graft copolymerization

the methacrylic acid and a potassium permanganate- sulfuric acid redox system were used as monomer and initiator

carboxyl groups was introduced successfully. Scanning electron microscope (SEM)

Fourier transform infrared spectrometer (FTIR) and zeta potential analysis were used to characterize corncob and the effects of adsorption conditions on the adsorption of Cd2+ in aqueous solutions and its mechanism analyzed. The results showed that the experimental data obtained could be represented with a Langmuir isotherm

the adsorption rate followed pseudo-second-order kinetics and the rate-controlling step was the chemical sorption. Under certain conditions the adsorption rate was affected by both intra-particle and film diffusion rates. The maximal adsorption capacities of Cd2+ for methacrylic acid grafted and crude corncobs were 28.00 mg·g-1 and 5.96 mg·g-1

respectively

indicating improvement of nearly 4 times (adsorption conditions: pH 7

the dosage 5 g·L-1

temperature 30℃

adsorption time 6 h). The adsorption was a spontaneous endothermic process

the higher the temperature was

the greater the degree of spontaneous. During the process of adsorbing Cd2+

the groups on the surface of grafted corncob

including carboxyl

hydroxyl

amide and methyl groups could play important roles. It was found that there existed some wrinkles and white particles on the surface of grafted corncob after adsorbing Cd2+

and its porosity disappeared and electronegativity increased.